A user wearing, on the head of the user, a head-mounted display (hereinafter referred to as an “HMD”) connected to a game machine plays a game by operating a controller or the like while viewing a screen displayed on the HMD. In the case of an ordinary stationary display, a visual field range of the user extends also to the outside of a screen of the display. Therefore, it may be impossible to concentrate on the screen of the display, and there may be a lack of a sense of immersion in the game. In that respect, when the user wears the HMD, the user does not view other than video displayed on the head-mounted display. Thus, effects of enhancing a sense of immersion in a video world and further enhancing an entertaining characteristic of the game are obtained.
In addition, when the HMD is provided with a head tracking function, and an image of a virtual space or the like displayed on the screen is updated so as to be interlocked with movement of the head of the user, the sense of immersion in the video is further improved, and operability of an application such as the game or the like is also improved.